[Cases Analysis of Hemoglobin H Disease Caused by HBA2:c.2T>C and HBA2:c.2delT Mutations].

OBJECTIVE:To investigate two cases of rare pathogenic genes, initiation codon mutations in HBA2 gene, combined with Southeast Asian deletion and their family members to understand the relationship of HBA2:c.2T>C and HBA2:c.2delT mutations with clinical phenotype. METHODS:The peripheral blood of family members was obtained for blood cell analysis and capillary electrophoresis hemoglobin analysis. Gap-PCR and reverse dot blotting (RDB) were used to detect common types of mutations in ɑ-thalassaemia gene. Sanger sequencing was used to analyze HBA1 and HBA2 gene sequence. RESULTS:Two proband genotypes were identified as --SEA/αα with HBA2:c.2T>C and --SEA/αα with HBA2:c.2delT. HBA2:c.2T>C/WT and HBA2:c.2delT/WT was detected in family members. They all presented with microcytic hypochromic anemia. CONCLUSION:When HBA2:c.2T>C and HBA2:c.2delT are heterozygous that can lead to static α-thalassemia phenotype, and when combined with mild α-thalassemia, they can lead to the clinical manifestations of hemoglobin H disease. This study provides a basis for genetic counseling.